Polymer electrolyte fuel cells are characterized in using a proton conductive polymer electrolyte membrane, and are devices that obtain electromotive force by allowing oxidizing gas such as oxygen to electrochemically react with fuel gas such as hydrogen. Such polymer electrolyte fuel cells have a structure in which two gas diffusion electrodes, including a catalyst layer with carbon powder on which a noble metal-based catalyst is supported as a main component and a gas diffusion electrode base material, respectively have a catalyst layer side thereof set to the inside, and are bonded to both sides of a polymer electrolyte membrane.
The gas diffusion electrode substrate is generally configured from a carbonaceous material, and the gas diffusion electrode substrates indicated below are known, for example.
Patent Document 1 discloses a porous carbon electrode substrate for fuel cells characterized by having a thickness of 0.05 to 0.5 mm, a bulk density of 0.3 to 0.8 g/cm3, and a bending strength of at least 10 MPa and deflection upon bending of at least 1.5 mm in a three-point bending test under the conditions of a strain rate of 10 mm/min, a distance between support points of 2 cm and a test piece width of 1 cm.
Patent Document 2 discloses a gas diffusion layer for fuel cells including a mat having a plurality of carbon fibers, and a plurality of acrylic pulp fibers incorporated into this carbon fiber mat, and that the acrylic pulp fibers are cured and carbonized after incorporation into the carbon fiber mat.
Patent Document 3 discloses a carbon fiber sheet having a thickness of 0.15 to 1.0 mm, a bulk density of 0.15 to 0.45 g/cm3, a carbon fiber content of at least 95% by mass, a compressive deformation rate of 10 to 35%, an electrical resistance value of no more than 6 mΩ, and a degree of drape of 5 to 70 g.
Patent Document 4 discloses a carbon fiber non-woven fabric for a polyelectrolyte fuel cell electrode material having a thickness of 0.15 to 0.60 mm, a basis weight of 50 to 150 g/m2, a specific resistance value in the thickness direction of no more than 0.20 Ωcm, and a surface pile number of no more than 15/mm2.
Patent Document 1: Pamphlet of PCT International Publication No. WO2001/056103
Patent Document 2: Japanese Unexamined Patent Application, Publication No. 2007-273466
Patent Document 3: Pamphlet of PCT International Publication No. WO2002/042534
Patent Document 4: Japanese Unexamined Patent Application, Publication No. 2003-45443